Flow Characteristics of Luer and non-Luer Spinal Needles

Monteiro RS, Pillai A, Choi SW et al

Anaesthesia 2017; 72: 749-754
DOI:10.1111/anae.13851/full

Background

In 2004, the National Patient Safety Agency advocated the introduction of a non-Luer system for delivery of neuraxial anaesthesia. The AAGBI anticipated that all neuraxial devices will change to incorporate the ISO 80369-6 non-Luer connector in the UK in 2017. Flow rates of 25-G and 27-G spinal needles (90-mm and 120-mm lengths) from Vygon, BD, B. Braun and Pajunk were measured, with either a Luer connector, or a Surety® or UniVia® non-Luer connector in an in-vitro study.

Method

A bench-top model of entering the spinal space, pressurised to 35 cmH2O to simulate cerebrospinal fluid pressure in the sitting position. The two endpoints studied were

  • Time to first appearance of simulated cerebrospinal fluid in the needle hub
  • Amount of fluid collected over 120 s after the needle was introduced

Results

The mean times to first appearance of fluid in the needle hub of Luer spinal needles varied from 0.36s (25-G 90-mm BD) to 3.14s (27-G 120-mm B. Braun), and in the non-Luer spinal needles from 0.22s (25-G 90-mm B. Braun) to 2.99s (27-G 120-mm Pajunk). There was a significant difference in the time to first appearance of fluid in the needle hub between Luer and non-Luer needles of the same type.

The mean weight of fluid collected in 120 s using the Luer spinal needles varied from 0.21g (27-G 120-mm Pajunk) to 1.21g (25-G 90-mm Vygon), and using the non-Luer spinal needles from 0.25g (27-G 120-mm Pajunk) to 1.55g (25-G 90-mm B. Braun). All of the needle types showed a greater weight of fluid collected using the non-Luer compared with the Luer version. Significant variations in flow were also seen between the same needle type from different manufacturers.

Conclusions

Changing from Luer to non-Luer versions of spinal needles may introduce important differences in function.

Journal Club Discussion : Potential risks

  • Use of unfamiliar spinal needles, slower flow rate, longer time to perform a lumbar puncture.
  • Significant differences between manufacturers, could be relevant if rotating between different hospitals thus resulting in using unfamiliar spinal needles.
  • Slower flow rate leading to longer time to perform lumbar punctures, may push needles in further than intended.
  • With non-Luer connectors, more “accessories” would be necessary e.g. epidural connectors/needles, drawing up needles, syringes etc, increasing costs of equipment.
  • Rarely may breach dura with introducer needle – would need to consider how to inject spinal drugs through introducer needle as connections would not be compatible.
  • It would make sense for any present plans to change to currently available non-Luer needles to wait until the new universal ISO 80369-6 non-Luer connector is available.

Summary by Dr M Rojo and Dr PY Kuo. Journal Club 17 August 2017.

 

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